Shaped charge perforating apparatus and method

ABSTRACT

Apparatus for perforating oil and gas wells and the like and methods for completing such wells in an unconsolidated formation. The apparatus includes one or more shaped charges having inert particles located therein arranged to be carried, upon detonation of the charge, into the perforation formed by the charge and also including a carrier for positioning the shaped charge in the well. The method includes the steps of positioning the shaped charge and carrier in the well adjacent the unconsolidated formation to be perforated and detonating the charge to simultaneously form the perforation and place the inert particles in the perforation to form a permeable bridge therein.

United States Patent 2,649,046 8/1953 Davis i.

Inventor Alexis A. Venghlattis Weston. Conn. Appl. No. 755,489 FiledJuly 26. 1968 Division of Ser. 50. 578.36. Sept. 1966. Pat. No. 3.0532].Patented June 29. I971 Assignee Dresser Industries Inc. Dallas, Tex.

SHAPED CHARGE PERFORATING APPARATUS AND METHOD 2 Claims, 7 Drawing Figs.

US. Cl

Int. Cl r Field of Search References Cited UNITED STATES PATENTS2.821,]36 l/l958 Castel l75/455 2,873,676 2/l959 Caldwell... l75/4.62,968,243 1/l96l Turechek .v l75/4.6 3,327,792 6/1967 Boop r. l75/4,55 X

Primary Examiner--David H. Brown Atlorneys- Robert W. Mayer. Russell E.Schlorff. Daniel Rubin, Peter J. Murphy, Roy L. Van Winkle and WilliamE. Johnson, Jr.

detonating the charge to simultaneously form the perforation and placethe inert particles in the perforation to form a permeable bridgetherein.

PATENTEDJUNZSIHH 3,589,453

sum 1 or 2 fll'Em-4 SHAPED CHARGE PERFORATING APPARATUS AND METHOD Thisis a division of application Ser. No. 578,216, filed Sept. 9, I966 nowPat. No. 3,4l5,32 I.

This invention relates generally to improved methods and apparatususeful in perforating oil and gas wells and the like. More particularly,but not by way of limitation, this invention relates to improvedperforating apparatus and methods for completing a well in anunconsolidated formation.

Generally, in the completion of oil and gas wells and the like, anelongated metal casing is positioned in the well bore. Due to theirregularity of the well bore and due to the difference in diameterbetween the well bore and the metal cas ing, a cementitious material isusually pumped into the annular space. The cementitious material servesto permanently fix the metal casing in the well bore and to preventmigration of well fluids through the annular space. It is obvious thatthe metal casing and the cementitious material disposed adjacent aproductive formation will prevent the flow of fluids from the formationinto the interior of the casing. Therefore, the prac tice has been toperforate the casing, cementitious material, and the formation by theuse of either shaped charge or bullet perforators. The perforators arelowered into the casing to a position adjacent the productive formationand then fired from the surface through an appropriate electricalcircuit.

The aforesaid procedure has been very successful, but a great deal ofdifficulty has been encountered when the productive formation consistsof an unconsolidated sand or similar substance. The particle size ofunconsolidated sands will vary between two one-thousandths of an inchand twenty one-thousandths of an inch while the diameter of theperforalion made with the usual perforators will be somewhere betweenone-fourth and three-fourths of an inch. As is obvious from theforegoing, even the largest sand particles are very small as compared tothe smallest diameter of perforation made by conventional perforatingapparatus. Thus, as well Fluids are produced through the perforationinto the interior of the casing, said particles will, more than likely,be produced therewith. If a sufficient quantity of sand is produced intothe :asing, the sand may accumulate therein and completely alock theproduction of well fluids or if pumping or valve apaaratus is disposedin the well, the sand may have a serious :rosive effect thereon.

One attempt made to solve the foregoing problem utilizes in array ofvery small bullet perforators fired simultaneously n a prearrangedpattern. Although the perforations made are no large in diameter to beuseful in preventing the migration )f sand into the casing, the bulletswill, when fired into friable :ementitious material, shatter thecementitious material formng a permeable bridge in the perforations toinhibit the migraion of the unconsolidated sand.

Another attempted solution involves the use of shaped :hargesconstructed to provide small diameter perforations. lowever, thediameter of the perforations are still sufficiently arge so that they donot effectively inhibit the flow of sand nto the casing. Unlike thebullet perforators, the shaped :harges form a clean hole or perforationand do not shatter he cementitious material even when the material isfriable. :herefore, small perforations formed by shaped charges have lotbeen effective to inhibit the flow of sand into the casing.

Very often in the completion of wells, a relatively small liameterproduction tubing will be run within the casing. 'ackers, of a type wellknown in the well tool art, or other imilar apparatus, are usuallyutilized to hold the tubing in the asing and to prevent the flow offluid through the annular pace between the tubing and casing. In suchinstances, the erforating apparatus must be run through the tubing priorto caching the zone to be perforated. Usually, the tubing terrinatesabove the producing formation so that the perforating pparatus isdisposed within the relatively large diameter of he casing when theperforator is tired.

To make the most efficient use of perforators, it is highly desirable tobe able to control the distance from the shaped charge or bullet to thecasing, that is, to control the standoff. Manifestly, perforatingapparatus small enough to be run through the tubing will have aconsiderable standoff when located in the casing and will not providethe optimum conditions for firing the bullets or shaped charges toperform the perforating operation in the most efficient manner.

SUMMARY OF THE INVENTION Generally, this invention provides improvedperforating apparatus including a carrier arranged to be moved throughthe well bore; a plurality of shaped charges carried by the carrier,each charge being oriented in a direction whereby the detonation thereofforms an explosive jet that perforates the formation, each chargeincluding a plurality of inert particles arranged to be carried into theperforations forming a permea ble bridge therein; and, ignition meansfor detonating the charges.

In another aspect, this invention contemplates the construc tion of ashaped charge that includes a plurality of inert particles that arecarried into the perforation and that are sized and shaped to form apermeable bridge therein.

Also, this invention provides a collapsible carrier whereby shapedcharges may be lowered through relatively small diameter tubing andpositioned in relatively larger diameter casing for efficientlyperforming the perforating operation. Additionally, this inventioncontemplates the construction of another carrier for the shaped chargesthat includes a member constructed from sheet explosive that holds anarray of charges and provides for their simultaneous detonation.

One object of the invention is to provide an improved method ofcompleting a well in an unconsolidated formation wherein permeablebridges are formed in the perforations to inhibit the migration of sandtherethrough.

Another object of the invention is to provide an improved perforatingapparatus wherein a selected array of shaped charges may besimultaneously detonated from a plurality of such arrays.

Still another object of the invention is to provide an improvedperforating apparatus arranged to form relatively small diameterperforations and to form permeable bridges therein.

The foregoing and additional objects and advantages of the inventionwill become more apparent as the following detailed description is readin conjunction with the accompanying drawings wherein like referencecharacters denote like parts in all views and wherein:

FIG. l is a cross-sectional view of a shaped charge constructed inaccordance with the invention;

FIG. 2 is a cross-sectional view similar to FIG. 1, but illustratinganother embodiment of shaped charge also constructed in accordance withthe invention;

FIG. 3 is a vertical cross-sectional view illustrating perforatingapparatus constructed in accordance with the invention disposed in acased well bore;

FIG. 4 is a cross-sectional view taken substantially along the line 4-4of FIG. 3;

FIG. 5 is an elevational view of another embodiment of perforatingapparatus also constructed in accordance with the in- SHAPED CHARGEReferring to the drawing and to FIG. 1 in particular, shown therein andgenerally designated by the reference character 10 is a shaped chargeconstructed in accordance with the invention. The shaped charge it]includes a hollow body l2, an

explosive material l4 partly filling the interior of the hollow body l2,and a cap 16 closing one end of the hollow body l2.

The explosive material l4 has a conical cavity 18 in the end thereofadjacent the cap l6. A liner 20, which is also of conical configuration,is located in the hollow body 12 in jux taposition with the surface ofthe explosive material 14 forming the cavity 18. The liner 20 may beconstructed from rela tively thin sheet metal, but is preferablyconstructed from a granular metal as disclosed in U.S. Pat. No.3,255,659 issued on June I4, 1966 to Alexis A. Venghiattis.

A plurality of particles 21 are located between the surface of theexplosive material l4 and the liner 20. The particles 2] are preferablyformed from an inert material and preferably have at least one dimensionthat is not less than one-half the diameter of the perforation that isformed upon detonation of the shaped charge [0.

FIG. 2 illustrates another embodiment of shaped charge generallydesignated by the reference character 22. The shaped charge 22 includesthe previously described hollow body 12 and explosive material 14. Oneend of the hollow body 12 is closed by a cap 24, which is constructedsimilarly to the cap 16 but, as is apparent from a comparison of P165 Iand 2, is more elongated to provide additional standoff for thrshapedcharge 22 for reasons that will he explained more full; hereinafter.

The opposite end of the hollow body 12 is closed by a seal ing cover 26.The sealing cover 26 is optional, but its use is preferred when theshaped charge 22 is used in open or capsule type carriers wherein theexplosive material 14 would otherwise be exposed to well fluids.

As illustrated in FIG. 2, the shaped charge 22 also includes theconically shaped cavity 18 that is formed in the explosive material 14and a conical liner 28 disposed in juxtaposition therewith. A pluralityof particles 30 are disposed in the liner 28. As previouslymentionedwith respect to the liner 20, the liner 28 is preferably formedas taught in U.S. Pat. No. 3,255,659.

As will be understood by those skilled in the art of shaped charges, theconical cavity 18 in the charges 10 and 22 produces the so-called Munroeeffect upon detonation that results in a high energy jet of sufficientenergy magnitude to form perforations. Preferably, the shaped charges 10and 22 are of a size that will result in the formation of a perforationhaving an average diameter of 0.050 inches. The particles 2] and 30 inthe shaped charges 10 and 22, respectively, are ar ranged to be carriedinto the perforation formed by the charges and are of such size andshape that they will form a permeable bridge therein for reasons thatwill be discussed.

PERFORATING APPARATUS OF FIG. 3

FIG. 3 illustrates perforating apparatus generally designated by thereference character 32 and disposed in a casing 34. As shOwn therein,the casing 34 is located in a well bore 36 and is retained therein bycementitious material 38 disposed in the annular space between the wallof the well bore 36 and the exterior ofthe casing 34.

The lower end of a relatively small diameter tubing 40 is il lustratcdas bein disposed within the casing 34. The tubing 40 is retained in acentral position in the casing 34 by a packer 42 that also serves toprevent the flow of fluid through the annu- In space between the tubing40 and the casing 34.

The perforating apparatus 32 is suspended in the casing 34 on a wireline or cable 44 that extends upwardly through the tubing 40 to thesurface (not shown) of the well bore 36. The cable 44 has sufficientmechanical strength to support the perforating apparatus 32 and alsocontains the necessary electrical conductors (not shown). The lower endof the cable 44 is connected to an adapter 46 that forms the upper endof the perforating apparatus 32.

The perforating apparatus 32 also includes a pair of shaped chargeholding members 48 that are disposed in generally parallel spacedrelationship and extend substantially parallel to the longitudinal axisof the casing 34. The upper end of each of the shaped charge holdingmembers 48 is connected by a hinge 50 with a linkage member 52. Theopposite end of each of the linkage members 52 is connected by a hinge54 with the adapter 46.

The lower end of each of the shaped charge holding members 48 isconnected by a hinge 56 with a linkage member 58. The lower ends of thelinkage members 58 are pivotally joined by a hinge 60. The hingedconnecting structure joining the shaped charge holding members 48provides an articulated linkage wherein the shaped charge holdingmembers 48 can move relatively together and relatively apart insubstantially parallel relationship.

A spring 62 is illustrated as being connected with the adapter 46 andhaving its free end portions in engagement with the linkage members 52.The spring 62 constantly biases the linkage members 52 and the holdingmembers 48 relatively apart.

Similarly, a spring 64 encircles the hinge 60 and has its free endportions in engagement with the linkages 58. The spring 64 serves tobias the linkages 58 and the holding members 48 relatively apart thusmaintaining the shaped charge holding members 48 in substantiallyspaced, parallel relationship As illustrated in HQ. 3 and also n FIG. 4the shaped charge holding members 48 each includes a plurality of heshaped charges 22 Manifestly, the shaped charge 10 could be utilized inlieu of shaped charge 22 as could any of the well-known constructions ofshaped charge. Preferably, the shaped charges used include a sealingcover, such as the cover 26 shown in FIG. 2, so that the explosivematerial 14 will not come into contact with fluids in the well bore 36.

The shaped charges 22 are each connected with some means for detonatingthe shaped charges. For example, FIGS, 3 and 4 illustrate a primacord 66connecting each of the charges 22 with a respective one of a pair ofboosters 68 and detonators 70. The detonators 70 are connected withwires 72 that extend upwardly through the adapter 46 and the cable 44 toa source of electrical energy (not shown) located on the surface (notshown) adjacent the upper end of the well bore 36, As is well known,electric current passing through the conductors 72 ignites thedetonators 70, boosters t8 and the in terconnected primacord 66.Manifestly, the ignition of thc primacord 66 detonates the shapedcharges 22 essentially simultaneously due to the high explosive natureof the prim :icorrt 66 OPERATION OF THE EMBODIMENT OF FIG. 3

To utilize the perforating apparatus 32, the shaped charges 22 aredisposed in the shaped charge holding members 48 in accordance with thedesired perforation pattern and number of perforations to be formed. Theadapter 46 is connected with the cable 44 and the perforating apparatus32 is then extended into the tubing 40. As will be apparent from viewingFIG. 3, the holding members 48 are moved relatively together,compressing the springs 62 and 64 to permit the insertion of theapparatus 32 into the relatively srnal. diameter tubing 40.

The apparatus 32 is then lowered through the tubing -1-6. passingthrough the open end thereof into the relatively larger diameter casing34. When the apparatus 32 is disposed adjacent the formation to beperforated, its downward movement is arrested and the apparatus 32 issuspended on the cable 44 in the well bore 36. The conductors 72 arethen energized igniting the detonators 70, boosters 68 and the primacord66. When the primacord 66 dctonates, the shaped charges 22 aresimultaneously detonated to form a plurality of perforations 74 asillustrated in F168. 3 and 4.

As the shaped charges 22 detonate, the perforations 74 are formedthrough the casing 34, the cementitious material 38, and extend into theformation surrounding the well bore 36. Simultaneously, the inertparticles 30 are carried into the perforations 74 as illustrated in FIG.4, forming permeable bridges therein to prevent or at least to inhibitthe migration of unconsolidated materials from the formation through theperforations 74 into the interior of the casing 34.

Generally, detonation of the shaped charges 22 disintegrates a largeportion of the shaped charge holding members 48 dropping the linkages 58into the lower portion of the well bore 36. For this reason, the linkagemembers 52 and 58 and the shaped charge holding members 48 arepreferably constructed from a material that is easily drillable, such asalu minum, or one of the plastics. After the detonation of the shapedcharges 22, the portion of the apparatus 32 remaining intact can beretrieved from the well bore 36 by withdrawing the cable 44 therefrom asis well known in the art.

it should be evident from the foregoing that utilizing the relativelysmall shaped charges 22 permits their close spacing in the holdingmembers 48 whereby the formation is perforated by a large number ofrelatively small perforations 74, that is, the formation is saturatedwith small diameter perforations 74 whereby a flow area of relativelylarge size is obtained. it will also be noted, that the shaped charges22 are properly positioned relative to the casing 34, that is, they willhave the desired standofi to perform the perforating operation in themost efficient manner due to the preselected length of the cap 24 (seeFIG. 2)v Thus, while the shaped charges 22 form relatively cleanperforations 74, the perforating apparatus 32 is effective inunconsolidated formations to form the desired perforations whileinhibiting the flow of sand from such formations due to the permeablebridge formed by the inert particles 30,

PERFORATING APPARATUS OF FIG. 5

FIG. 5 illustrates another embodiment of perforating apparatus generallydesignated by the reference character 100. As shown therein, theperforating apparatus 100 is suspended in a well bore 102 on a cable104. The cable 104 includes members of sufficient structuralstrength tosupport the per forating apparatus 100 as well as including thenecessary electrical conductors for detonating the perforating apparatus100 as will be described.

The perforating apparatus 100 also includes an adapter 106 that isconnected with the cable 104 and a selective ignition control device 108that is constructed as described in U.S, Pat. No. 3,221,655 issued Dec.7, 1965 to Alexis A. Venghiattis. Connected with the lower end of theselective ignition control means 108 is a plurality of identicallyconstructed shaped charge carriers 110.

As is evident from viewing HO. 5, the shaped charge carriers 110 arearranged in end-to-end relationship. The number of shaped chargecarriers 110 utilized depends upon the number and concentration ofperforations desired. Manifestly, and although not illustrated, spacerscan be utilized between the shaped charge carriers 110 to provide anydesired spacing.

FIG. 6 illustrates in more detail the construction of the shaped chargecarriers 110. As shown therein, each of the shaped charge carriers 110includes a tubular housing 112 having a closed upper end 114 and athreaded lower end 116. A plug 118 is threaded into the lower end 116 ofthe housing 112 thereby closing the lower end 116 thereof. The upper end114 of the tubular housing 112 is partially threaded as shown at 120 toreceive the plug 118 forming a portion of the adjacent shaped chargecarrier 110.

The tubular housing 112 is provided with a plurality of apertures 122that extend through the wall thereof. Closure members 124 are pressedinto the apertures 122 to close the apertures 122 against the entranceof well fluids. The tubular housing 112 is constructed to withstand thepressures encountered within the well bore 102.

A cylindrical shaped charge holding member 126 is disposed substantiallycoaxially within the tubular housing 112 with its upper end abutting theend 114 of the housing 112 and is lower end abutting the plug 118. Thecylindrical holding member 126 is provided with a slot 128 for receivingone end of a partially threaded pin 130 to align the chai'ge holdingmember 126 in the housing 112 for reasons that will be described. Thepartially threaded pin extends through the wall ofthe tubular housing112 and into the slot 128 as shown.

A plurality of shaped charges 10 are located in the holding member 126and each is aligned with a respective one of the apertures 122. Thealignment of the shaped charges 10 with the apertures 122 is assured bythe relationship of the slot 128 and the partially threaded pin 130.

As illustrated in the upper portion of FIG. 6, electrical conductors 132and 134 extend through an opening 136 formed in the sidewall of thetubular housing 112. The opening 136 is provided to protect theelectrical conductors from damage as the perforating tool 100 passesthrough the well bore 1027 The conductor 132 extends through the wall ofthe tubular housing 112 and is connected with a detonator and boaster138 which is in turn connected with a primacord 140, The primacord 140is connected with each of the shaped charges 10 within a single carrier110 whereby all the shaped charges 10 contained therein will besimultaneously detonated.

As shown in the lower portion of FIG. 6, the conductor 134 extendsthrough the tubular housing 112 of the subjacent carrier 110 and,although not shown, will be connected to the shaped charges therein aspreviously described. It will of course to be understood that theelectrical conductors 132 and 134 are electrically interconnected withthe electrical conductors (not shown) contained in the cable 104 andextend to the surface (not shown) adjacent the well bore 102 whereinthey will be connected to a source of electrical poten tial (not shown).

OPERATION OF THE PERFORATINO APPARATUS OF FIG. 5

The perforating apparatus 100 is lowered into the well bore 102 on thecable 104 until it is adjacent the formation or zone to be perforated.When the zone to be perforated is reached, the perforating apparatus 100is suspended by the cable 104 and the downward movement thereofterminated,

One of the conductors, conductor 132 for example, is energized throughthe selective ignition control 108 as described in the previouslymentioned Venghiattis U.S. Pat. No. 3,22 l ,655 to detonate the shapedcharges 10 contained in the interconnected shaped charge carrier 110. Itshould be emphasized that only the shaped charges 10 in the selectedcarrier 110 will be detonated.

When the shaped charges 10 detonate, the explosive jet formed therebyperforates the cover 124 and extends into the formation forming thenumber and arrangement of perforations therein as predetermined by thenumber and distribution of charges in the carrier 110. Manifestly, theperforating apparatus 100 may also be used in cased and cemented wellsas previously described in connection with the perforating apparatus 32.

After the shaped charges 10 have been detonated in a selected one of thecarriers 110, the remaining carriers 110 may be actuated to detonate theshaped charges 10 contained therein or the perforating apparatus 100 maybe raised or lowered to a different formation prior to the detonation ofthe shaped charges in each of the carriers 110.

As will be understood from the foregoing detailed description of theshaped charges 10, they are very small and are capable of formingrelatively small perforations whereby a large number of the shapedcharges 10 may be contained within a single carrier 110. Thus, theformation adjacent the shaped charge carrier 110 will be saturated withrelatively small perforations formed by the shaped charges 10.

FIG. 7 illustrates a modification of the shaped charge apparatus 100.More specifically, FIG. 7 illustrates a shaped charge holding member,designated by the reference character 150, that can be utilized in lieuof the shaped charge holding member 126.

Although only a portion of the cylindrical charge holding member isillustrated it will be understood that it will extend the full length ofthe tubular housing 112 as did the holding member 120. The shaped chargeholding member 150 is constructed from a sheet explosive and therebyeliminates the necessity for the primacord 140 illustrated in FIG. 6.

It will be noted in FIG. 7 that the conductor I32 and the detonator andbooster 138 are connected directly to the holding member 150. The shapedcharges 10 are planted directly in the holding member [50 and arearranged to be simultaneously detonated thereby upon detonation of thedetonator and booster I38.

Manifestly, the operation of the perforating apparatus with the shapedcharge holding member 150 therein will be substantially the same as withthe shaped charge holding member [26 therein. The charge holding member150 has the advantage of eliminating the necessity for interconnectingthe shaped charges 10 with the primacord 140. Thus, there is less chanceof detonation failure when using the holding member 150.

It will also be understood that the perforating apparatus 100 utilizingeither the shaped charge holding member 126 or the shaped charge holdingmember 150 can be effectively utilized to perforate unconsolidated sandsas previously described in connection with the perforating apparatus 32.The shaped charges 10 also include the inert particles 21 (see FIG 1) sothat the perforation formed thereby will also include a permeable bridgeto inhibit the flow of sand through the perforations it will beunderstood that the embodiments described in detail hereinbefore arepresented by way of example only and many changes and modifications canbe made thereto without departing from the spirit of the invention orfrom the scope of the annexed claims.

What I claim is:

l. Perforating apparatus for use in completing a well com prising:

a tubular housing having an upper closed end, a lower closed end. and aplurality of apertures extending transversely through the wall of saidhousing;

closure means closing each of said apertures;

a plurality of shaped charges located in said housing;

generally cylindrical-shaped charge holding means located substantiallycoaxially in said housing and holding each said shaped charge inalignment with a respective one of said apertures; and

ignition means extending into said housing for detonating said charges;

said holding means being constructed from a sheet explosive; and

said ignition means extending into said housing and being connected withsaid sheet explosive.

2. Perforating apparatus for use in completing a well comprising:

a plurality of tubular housings, each said housing having upper andlower closed ends and a plurality of apertures extending through thewall thereof, said housings being connected in end-to-end relationship;

closure means closing each said aperture;

a plurality of shaped charges disposed in each said housing;

a generally cylindrical-shaped charge holding member locatedsubstantially coaxially in each said housing holding each said charge inalignment with a respective aperture;

selective ignition control means connected with one of said housings;and,

ignition means connecting said control means with said charges, wherebythe shaped charges located in a selected housing are simultaneouslydetonated,

said holding means being constructed from a sheet explosive and beingoperably connected with said ignition means.

1. Perforating apparatus for use in completing a well comprising: atubular housing having an upper closed end, a lower closed end, and aplurality of apertures extending transversely through the wall of saidhousing; closure means closing each of said apertures; a plurality ofshaped charges located in said housing; generally cylindrical-shapedcharge holding means located substantially coaxially in said housing andholding each said shaped charge in alignment with a respective one ofsaid apertures; and ignition means extending into said housing fordetonating said charges; said holding meAns being constructed from asheet explosive; and said ignition means extending into said housing andbeing connected with said sheet explosive.
 2. Perforating apparatus foruse in completing a well comprising: a plurality of tubular housings,each said housing having upper and lower closed ends and a plurality ofapertures extending through the wall thereof, said housings beingconnected in end-to-end relationship; closure means closing each saidaperture; a plurality of shaped charges disposed in each said housing; agenerally cylindrical-shaped charge holding member located substantiallycoaxially in each said housing holding each said charge in alignmentwith a respective aperture; selective ignition control means connectedwith one of said housings; and, ignition means connecting said controlmeans with said charges, whereby the shaped charges located in aselected housing are simultaneously detonated, said holding means beingconstructed from a sheet explosive and being operably connected withsaid ignition means.